The Department of Microbiology at The University of Texas Medical Branch is seeking funds for the purchase of a Coulter Elite flow cytometer to enable scientists within the department to pursue a wide range of important questions, including studies on: 1) the pathogenesis of HIV; 2) the development of autoimmune disease; 3) mechanisms of immunodeficiency due to hereditary ADA deficiency; 4) the interplay between the immune- neuroendocrine networks; 5) the pathogenesis of bacteria in the gut; 6) mechanistic studies of the natural cytotoxic activity against bacteria- infected cells; 7) the molecular events associated with lymphocyte activation; and 8) the role of proto-oncogenes in cellular metabolism and oncogenesis. Of the ten individual scientists who have an immediate need for the technical capabilities of the Elite, seven currently are funded through NIH grants, while the remaining investigators are funded by other sources. Additionally, new thematic programs that have recently been established, either within the Department of Microbiology or in close collaboration with other departments, further increase the need for advanced flow cytometric capability in order to aggressively pursue their goals. These programs provide substantial new funds from the University and the NIH for support of the proposed instrumentation. It is our goal to establish a core flow cytometry facility within the department, consisting of a Coulter Profile flow cytometer, which currently is operated and maintained by the department, and the Coulter Elite. Such a facility would provide the capability to pursue scientific questions using virtually every available flow cytometric technique. While we have projected that members within the department will constitute the major user population for the facility, faculty outside the department will be encouraged to use the facility as well. Thus, we feel that we will be able to provide an extremely valuable research capability that benefits the entire scientific community at UTMB. The Principal Investigator (PI) will provide administrative oversight for flow facility operations, which will be directly supervised by personnel who are well trained in the operation of flow cytometry equipment. Additional administrative and fiscal oversight will be provided by the administrative committee for flow cytometry. A full commitment by UTMB for personnel support and space is enclosed.